// 如果图像 rescale,  fill 画出的圆盘会变形; 注意 x y轴的尺寸分别为 50, 10
settings.outformat = "pdf";
size(5cm, 5cm, keepAspect = false);
draw((0, 0)--(50, 0), arrow = Arrow(TeXHead));
draw((0, 0)--(0, 10), arrow = Arrow(TeXHead));
real r = 0.5;
fill(circle((2, 1), r));
fill(circle((35, 8), r));
fill(circle((42, 9), r));